Turbine cooling system and method

ABSTRACT

A turbine blade of a gas turbine engine is disclosed. The blade may comprise a first cooling passage and a second cooling passage, where the second cooling passage may be located adjacent a leading edge of the blade. The blade may further comprise at least one slot formed in a partition disposed between the first and second cooling passages, and at least one turbulator disposed within the second passage and downstream the at least one slot.

TECHNICAL FIELD

The present disclosure relates generally to gas turbine engine cooling,and more particularly to the cooling of turbine blades in a gas turbineengine (GTE).

BACKGROUND

GTEs produce power by extracting energy from a flow of hot gas producedby combustion of fuel in a stream of compressed air. In general, turbineengines have an upstream air compressor coupled to a downstream turbinewith a combustion chamber (“combustor”) in between. Energy is releasedwhen a mixture of compressed air and fuel is burned in the combustor. Ina typical turbine engine, one or more fuel injectors direct a liquid orgaseous hydrocarbon fuel into the combustor for combustion. Theresulting hot gases are directed over blades of the turbine to spin theturbine and produce mechanical power.

High performance GTEs include cooling passages and cooling fluid toimprove reliability and cycle life of individual components within theGTE. For example, in cooling the turbine section, cooling passages areprovided within the turbine blades to direct a cooling fluidtherethrough. Conventionally, a portion of the compressed air is bledfrom the air compressor to cool components such as the turbine blades.The amount of air bled from the air compressor, however, is usuallylimited so that a sufficient amount of compressed air is available forengine combustion to perform useful work.

U.S. Pat. No. 5,603,606 to Glezer et al. (the '606 patent) describes asystem for cooling airfoils, such as turbine blades and nozzles, in aGTE. According to the system described in the '606 patent, cooling fluidfrom the compressor section of the GTE is directed through a coolingpath of a turbine blade. The turbine blade includes a plurality of holesor slots, which act as a means for swirling a portion of the coolingfluid through the turbine blade. The cooling fluid flows out of theplurality of holes or slots and into an empty gallery, where the coolingfluid swirls radially along the gallery.

SUMMARY

In one aspect, a turbine blade of a gas turbine engine is disclosed. Theblade may comprise a first cooling passage and a second cooling passage,where the second cooling passage may be located adjacent a leading edgeof the blade. The blade may further comprise at least one slot formed ina partition disposed between the first and second cooling passages, andat least one turbulator disposed within the second passage anddownstream of the at least one slot.

In another aspect, a system for cooling a turbine blade of a gas turbineengine is disclosed. The system may include a first cooling pathdisposed in an interior of the turbine blade and configured to receive aflow of cooling fluid, and a second cooling path disposed in theinterior of the turbine blade and configured to receive the flow ofcooling fluid. A plurality of passages may form each of the first andsecond cooling paths, and a plurality of slots may be formed in apartition disposed between two of the plurality of passages forming thefirst cooling path. The plurality of slots may be configured to guidethe flow of cooling fluid through the first cooling path, and at leastone turbulator may be disposed downstream of the flow of cooling fluidflowing through the plurality of slots.

In yet another aspect, a method of cooling a turbine blade of a gasturbine engine is disclosed. The method may include flowing a coolingfluid through a plurality of passages and through at least one slotformed in a partition disposed between two of the plurality of passages.The method may further include adding turbulence to at least part of theflow of cooling fluid downstream of the at least one slot, theturbulence being adjacent a leading edge of the turbine blade.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a portion of a turbine section of a gasturbine engine;

FIG. 2 is an enlarged sectional view of a turbine blade taken alonglines 2-2 of FIG. 1;

FIG. 3 is an enlarged view of a portion of the turbine blade of FIG. 2along line 3;

FIG. 4 is an enlarged sectional view of the turbine blade of FIG. 2taken alone line 4-4.

FIG. 5 is an enlarged view of a portion of a turbine blade showinganother embodiment of a turbulator; and

FIG. 6 is an enlarged view of a portion of a turbine blade showing yetanother embodiment of a turbulator.

DETAILED DESCRIPTION

FIG. 1 illustrates a sectional view of a portion of a GTE, specificallya turbine section 10 of the GTE. The turbine section 10 includes a firststage turbine assembly 12 disposed partially within a first stage shroudassembly 20.

During operation, a cooling fluid, designated by the arrows 14, flowsfrom the compressor section (not shown) to the turbine section 10.Furthermore, each of the combustion chambers (not shown) are radiallydisposed in a spaced apart relationship with respect to each other, andhave a space through which the cooling fluid 14 flows to the turbinesection 10. The turbine section 10 further includes a fluid flow channel16 through which the cooling fluid 14 flows.

The turbine section 10 shown in FIG. 2 includes the first stage turbineassembly 12, which includes a rotor assembly 18 radially aligned withthe shroud assembly 20. The rotor assembly 18 may be of a conventionaldesign including a plurality of turbine blades 22. Each of the turbineblades 22 may be made from a variety of materials. The rotor assembly 18further includes a disc 24 having a plurality of circumferentiallyarranged root retention slots 30. The plurality of turbine blades 22 arereplaceably mounted within the disc 24. Each of the plurality of blades22 may include a first end 26 having a root section 28 extendingtherefore which engages with one of the corresponding root retentionslots 30. The first end 26 may be spaced away from a bottom of the rootretention slot 32 in the rotor assembly 18 to form a cooling fluid inletopening 34 configured to receive cooling fluid 14. Each turbine blade 22may further include a platform section 36 disposed radially outward froma periphery of the disc 24 and the root section 28. Additionally, anairfoil 38 may extend radially outward from the platform section 36.Each of the plurality of turbine blades 22 may include a second end 40,or tip, positioned opposite the first end 26 and adjacent the airfoil38.

As is more clearly shown in FIGS. 2, 3, and 4, each of the plurality ofturbine blades 22 includes a leading edge 42, and a trailing edge 44positioned opposite the leading edge 42. Interposed the leading edge 42and the trailing edge 44 is a pressure, or concave, side 46 and asuction, or convex, side 48 of the turbine blade 22. Each of theplurality of turbine blades 22 may have a generally hollow configurationforming a peripheral wall 50, which, in some embodiments, may have auniform thickness.

As shown in FIGS. 2, 3, and 4, an arrangement 52 for internally coolingeach of the turbine blades 22 is provided. The arrangement 52 forinternal cooling may include a pair of cooling paths 64 and 76 (FIG. 4),each described in more detail below, positioned within the peripheralwall 50, and separated from one another; however, any number of coolingpaths could be used.

A first cooling path 64 positioned within the peripheral wall 50 isinterposed the leading edge 42 and the trailing edge 44 of each of theblades 22. The first cooling path 64 includes a first passage 54extending between the first end 26 and the second end 40 of the turbineblade 22. Further included in the first cooling path 64 is a secondpassage 56, which extends between the first end 26 and the second end 40of the turbine blade 22. The second passage 56 is interposed the leadingedge 42 and the first passage 54 by a first partition 60, which isconnected to the peripheral wall 50 at both the pressure side 46 and thesuction side 48 of the turbine blade 22.

As shown in FIGS. 2, 3 and 4, at least one slot 58 is positioned in thefirst partition 60 in fluid communication with the first passage 54 andthe second passage 56. The slot, which may be a plurality of slots 58 asshown in the figures, is positioned adjacent the peripheral wall 50 nearthe pressure side 46 of each of the turbine blades 22.

A turbulator or turbulator element 62 configured to produce a turbulentfluid flow is disposed on the peripheral wall 50 in the second passage56. In some embodiments, the turbulator element 62 may be formedintegrally with the peripheral wall 50. As shown in FIGS. 2 and 3, theturbulator element 62 is disposed in a flow path of the cooling fluid 14downstream of the slot 58 and upstream of the leading edge 42, such thatthe turbulator element 62 is aligned with the flow of cooling fluid 14exiting the slots 58. In one instance, as shown in FIGS. 2, 3, and 4, asingle turbulator element in the form of a radial trip-strip may bedisposed in the second passage 56. If provided as a trip-strip, theturbulator element 62 may have any cross-section, for example arectangular cross-section, as shown in FIGS. 2 and 3. As shown in FIG.4, the turbulator element 62 may extend radially within the secondpassage 56 directly downstream of each of a plurality slots 58. AlthoughFIG. 4 shows the turbulator element 62 downstream of each one of aplurality of slots 58, the turbulator element 62 may have any length soas to be downstream of any number of slots 58 provided in the firstpartition 60.

In some embodiments, a plurality of turbulator elements 62 may beprovided in the second passage 56. For example, a plurality of radiallydisposed trip strips, like the trip strip shown in FIGS. 2, 3, and 4,could be disposed on the peripheral wall 50 in the second passage 56downstream of the slots 58. In other embodiments, the turbulator element62 may be a plurality of broken ribs arranged on the peripheral wall 50at different angles within the second passage 54. In yet otherembodiments, as shown in FIGS. 5 and 6 and as described in more detailbelow, the turbulator 62 may take the form of one or more concavecavities, or dimples 62 a, in the peripheral wall 50 and/or one or moreconvex protrusions 62 b formed on the peripheral wall 50 of the secondchamber 56. The one or more concave dimples 62 a or the one or moreconvex protrusions 62 b may otherwise be located and arranged asdiscussed above with respect to the turbulator elements 62, includingarranged as a plurality of concave dimples 62 a or convex protrusions 62b. The plurality of concave dimples 62 a may be formed at variouslocations in the peripheral wall 50 in the second passage 56, and theplurality of convex protrusions 62 b may be formed at various locationson the peripheral wall 50 in the second passage 56.

As shown in FIG. 3, the turbulator element 62 has a turbulator elementheight D1, representing the distance that the turbulator element 62extends from the peripheral wall 50 into the second passage 56. Asfurther shown in FIG. 3, the slot 58 has a slot height D2, representingthe open space through which the cooling fluid 14 can flow from thefirst passage 54 to the second passage 56, as described in more detailbelow. Furthermore, the turbulator element 62 is spaced from the slotinlet opening by a distance D3, which may be measured from where thecooling fluid 14 first enters the slot 58 to a front face of theturbulator element 62.

In some embodiments, a turbulator element 62 is provided having aturbulator element height D1 depending on the slot height D2. Forexample, a specified ratio of slot height D2 to turbulator elementheight D1 may be used to determine the turbulator element 62 to providein the second passage 56. In one instance, a ratio of the slot height D2to the turbulator element height D1 may be about 2 to 1, such that theslot height D2 is approximately two times the turbulator element heightD1. For example, a turbine blade 22 may be provided having a slot heightD2 of about 0.6100 mm (0.024 inches), in which case a correspondingturbulator element 62 may be provided having a turbulator element heightD1 of about 0.305 mm (0.012 inches).

The distance D3 between the turbulator element 62 and the slot inletopening may also depend on both the turbulator element height D1 and theslot height D2. For example, as described above, a larger turbulatorelement 62 (i.e. a turbulator element 62 having a greater turbulatorelement height D1) may be provided for a larger slot (i.e. a slot 58having a greater slot height D2). Additionally or alternatively, thedistance D3 may increase proportionately to an increase in slot heightD2. For example, a ratio of the distance D3 to the slot height D2 may beless than about 4 to 1, or about 3.5 to 1. Thus, the distance D3 fromthe slot inlet opening to the turbulator or turbulator element 62 may beless than about four times the slot height D2, or about three and onehalf times the slot height D2. In one instance, for a turbine bladehaving a slot 58 with a slot height D2 of about 0.6100 mm (0.024inches), a corresponding distance D3 may be about 2.16 mm (0.085inches).

As shown in FIGS. 2 and 3, a cross-sectional view of the second passage56 has a pre-established cross-sectional configuration. A generallyarcuate portion 96 adjacent the leading edge 42, a generally straightportion 98 following along the first partition 60, and the intersectiontherebetween form an angle 100. In some embodiments, the angle 100 maybe acute, for example between 45 and 60 degrees. In other embodiments,however, the angle may be less than 45 degrees, for example 30 degreesor less, or the angle may be greater than 60 degrees, for example 75degrees or more. As further shown in FIGS. 2 and 3, a plurality ofapertures 102, only one of which is shown, may each have a predeterminedcross-sectional area, and may each communicate between the secondpassage 56 and the suction side 48 of the turbine blade 22. In someembodiments, the cross-sectional area of the apertures 102 may be abouthalf the size of a cross-sectional area of the second passage 56. Theplurality of apertures 102 provide outlets on the suction side 48 at aninclined angle generally directed from the leading edge 42 toward thetrailing edge 44. The plurality of apertures 102 may be arranged asshowerhead apertures on the suction side 48 for showerhead film coolingof the turbine blade 22.

As mentioned above with respect to FIG. 1, a cooling fluid inlet opening34 provided adjacent the first end 26 of the turbine blade 22 isconfigured to receive cooling fluid 14 from first flow channel 16. Thecooling fluid inlet opening 34 is connected to the first and secondcooling paths 64 and 76, respectively. As shown in FIG. 4, the firstcooling path 64 includes a first cooling path inlet opening 66originating at the first end 26 of the turbine blade 22. The firstpassage 54 of the first cooling path 64 extending outwardlysubstantially an entire length of the turbine blade 22 toward the secondend 40 of the turbine blade 22. The second passage 56 includes theturbulator element 62 and is in communication, for example fluidcommunication, with a first horizontal passage 68. The first horizontalpassage 68 may be at least partially interposed the second end 40 of theturbine blade 22 and the first passage 54 by a second partition 70,which is connected to the peripheral wall 50 at both the pressure side46 and the suction side 48. The second passage 56 has an end 72 adjacentthe first end 26 of the turbine blade 22. The first horizontal passage68 communicates with a first cooling path outlet opening 74 disposed inthe trailing edge 44 of the turbine blade 22.

FIG. 4 also shows a plurality of the slots 58 extending radially betweenthe end 72 of the second passage 56 and an end 192 of the first passage54, where the end 192 of the first passage 54 is positioned opposite thefirst end 26 of the turbine blade 22. In some embodiments, an angledpassage 194 may extend between the first passage 54 and the secondpassage 56. The angled passage 194 enters the end 72 of the secondpassage 56 at an angle, which, in some embodiments, may be about 30 to60 degrees.

FIG. 4 further illustrates a second cooling path 76 positioned with theperipheral wall 50 and interposed the first cooling path 64 and thetrailing edge 44 of each turbine blade 22. The second cooling path 76 isseparated from the first cooling path 64 by a first wall member 80. Thesecond cooling path 76 includes a second cooling path inlet opening 78originating at the first end 26 of the turbine blade 22 and has a radialthird passage 82 extending outwardly substantially the entire length ofthe turbine blade 22 toward the second end 40 of the turbine blade 22.The second cooling path inlet opening 78 and the third passage 82 areinterposed the first cooling path 64 and the trailing edge 44. Furtherincluded is a second horizontal passage 84 positioned inwardly of thefirst horizontal passage 68 of the first cooling path 64 and is incommunication with the third passage 82 and a fourth passage 86. Thefourth passage 86 extends radially inwardly from the second horizontalpassage 84 to a third horizontal passage 88. The third horizontalpassage 88 communicates with a generally radial second cooling pathoutlet opening 90 disposed at the trailing edge 44 of the turbine blade22. The third passage 82 is separated from the fourth passage 86 by asecond wall member 92 which is connected to the peripheral wall 50 atthe pressure side 46 and the suction side 48. The fourth passage 86 isseparated from the second cooling path outlet opening 90 by a third wallmember 94 that is also connected to the peripheral wall 50 at thepressure side 46 and the suction side 48.

The aforementioned description is of the first stage turbine assembly12; however, it should be known that the construction could be typicalof the remainder of the turbine stages within the turbine section 10where cooling may be employed.

INDUSTRIAL APPLICABILITY

The described system may be applicable to turbine blades of a GTE.Additionally, although the system has been described with respect toturbine blades in the first stage turbine assembly, the system may beapplied to any turbine blade in any stage of the turbine section of aGTE. Furthermore, although the above-mentioned cooling system has beendescribed for cooling a turbine blade, the system may be adapted to anyairfoil, for example a first stage nozzle and shroud assembly.Additionally, the cooling system may be applied to any localizedstructure subject to heat that involves air flows and hot fluidtemperatures. Moreover, the described cooling system may be applied in avariety of industries, for example, heat exchange, energy, aerospace, ordefense.

The following operation will be directed to the first stage turbineassembly 12; however, the cooling operation of other airfoils and stages(turbine blades or nozzles) could be similar.

A portion of the compressed fluid from the compressor section of the GTEis bled from the compressor section and forms the cooling fluid 14 usedto cool the first stage turbine blades 22. The compressed fluid exitsthe compressor section, flows through a combustor discharge plenum andenters into a portion of the fluid flow channel 16 as cooling fluid 14.The flow of cooling fluid 14 is used to cool and prevent ingestion ofhot gases into the internal components of the GTE. For example, the airbled from the compressor section flows into a compressor dischargeplenum, through spaces between a plurality of combustion chambers, andinto the fluid flow channel 16 (FIG. 1). After passing through the fluidflow channel 16 in the turbine blade 22, the cooling fluid enters thecooling fluid inlet opening 34 between the first end 26 of the turbineblade 22 and the bottom 32 of the root retention slot 30 in the disc 24.The cooling fluid inlet opening 34 is fluidly connected to the first andsecond cooling paths 64 and 76, respectively, in the interior of theturbine blade 22.

As shown in FIG. 4, a portion of the cooling fluid 14, after havingpassed through the cooling fluid inlet opening 34 (FIG. 1), enters thefirst cooling path 64. The cooling fluid 14 enters the first coolingpath inlet opening 66 from the cooling fluid inlet opening 34, andtravels radially along the first passage 54, absorbing heat from theperipheral wall 50 and the first wall member 80. An amount of thecooling fluid 14, for example a majority of the cooling fluid 14, exitsthe first passage 54 through the plurality of slots 58.

The cooling fluid 14 flows through the slots 58 and over the turbulatorelement 62 creating a turbulent swirling flow that travels at leastpartially along the arcuate portion 96 of the second passage 56 in aradial direction, as shown in FIG. 3, absorbing heat from the leadingedge 42 of the peripheral wall 50. The cooling fluid 14 may flowdirectly from the slots 58 to the turbulator element 62, such that thecooling fluid 14 flows in an unimpeded path from the slots 58 to theturbulator element 62. Thus, the turbulator element 62 may be said to bedirectly downstream of the slots 58. The cooling fluid 14 flows over theturbulator element 62 such that laminar flow is turned into turbulentflow through at least the second passage 56. As mentioned above, theturbulator element 62 may be disposed on the peripheral wall within thesecond passage 56 such that all of the cooling fluid 14 flowing throughthe slots 58 flows over the turbulator element 62. In some embodiments,however, only a portion of the cooling fluid 14 flowing through theslots 58 from the first passage 54 into the second passage 56 may flowover the turbulator element 62. As noted above, a plurality ofturbulator elements 62 may be disposed in the second passage 56 suchthat the cooling fluid 14 flows over the plurality of turbulatorelements 62.

A portion of the cooling fluid 14 may also exit the plurality ofapertures 102, cooling a skin of the peripheral wall 50 in contact withcombustion gases on the suction side 48 prior to mixing with thecombustion gases. The remainder of the cooling fluid 14 in the firstcooling path 64 exits the first cooling path outlet opening 74 in thetrailing edge 44 to also mix with the combustion gases.

A second portion of the cooling fluid 14, after having passed throughthe cooling fluid inlet opening 34 (FIG. 1), enters the second coolingpath 76. For example, cooling fluid 14 enters the second cooling pathinlet opening 78 from the cooling fluid inlet opening 34, and travelsradially along the third passage 82 absorbing heat from the peripheralwall 50, the first wall member 80, and the second wall member 92 beforeentering the second horizontal passage 84, where more heat is absorbedfrom the peripheral wall 50. As the cooling fluid 14 enters the fourthpassage 86, additional heat is absorbed from the peripheral wall 50, thefirst wall member 80, and the second wall member 92 before entering thethird horizontal passage 88 and exiting the second cooling path outletopening 90 along the trailing edge 44 to be mixed with the combustiongases.

Current swirl-cooling technology may be prone to manufacturingchallenges due to a small slot height D2 (FIG. 3) provided for optimumoperation. For example, having a small slot height D2 may shortenturbine blade core die life due to accelerated core die wear at theportion of the die forming the slot inlet. The small slot height D2 mayalso cause high pressure losses that penalize the back-flow margin forblade tip film-cooling. Increasing the slot height D2 alone would leadto a decrease in the velocity of cooling fluid flowing through the slots58 and a decrease in pressure, which may in turn lead to less effectivecooling of the turbine blade 22.

The above-described system provides more efficient use of the coolingair bled from the compressor section of a GTE in order to facilitateincreased component life and efficiency of the GTE. The swirling andturbulence of the cooling fluid 14 contributes to the efficiency of thecooling fluid 14 flow as the cooling fluid 14 passes through the turbineblade 22. Increasing the slot height D2 and providing a turbulatorelement 62 downstream of the slot 58 may decrease pressure losses, whichmay in turn improve cooling effectiveness downstream of the slot 58.Furthermore, efficiency is facilitated within the internal portion ofthe turbine blade 22 along the leading edge 42, downstream of theturbulator element 62.

Specifically, the swirling action caused by the arrangement of slots 58in the first partition 60 and the turbulator element 62 in the secondpassage 56, the arcuate configuration of the arcuate portion 96 of thesecond passage 56, along with the flow of cooling fluid 14 through theangled passage 194, cause the cooling fluid 14 to generate a vortex flowin the second passage 56. The vortex flow caused by the slots 58 andturbulator element 62 leads to high local turbulence (vortices) alongthe arcuate portion 96 adjacent the leading edge 42 of the turbine blade22. Turbulent flow, as opposed to laminar flow, has more energy forcooling components such as turbine blades 22. The portion of the coolingfluid 14 entering the angled passage 194 between the first passage 54and the second passage 56 adds to the vortex flow by directing thecooling fluid 14 generally radially outward from the second passage 56into the first horizontal passage 68. The cooling fluid 14 takes on ascrew-type flow from the end 72 of the second passage 56 toward thefirst horizontal passage 68, which adds to the cooling efficiency inorder to better cool the turbine blade 22.

The above-described system enables use of slot having a greater height,and thus easier and less costly to manufacture, without suffering fromundesirable reductions in cooling performance, by use of a turbulatorelement. The turbulator element compensates for a reduced swirl coolingfluid velocity through the slot due to a larger slot height, and alsoincreases the back-flow margin for blade tip film-cooling. As mentionedabove, the size, specifically the height, of the turbulator elementprovided may depend on the slot height. Using a predetermined desiredratio of slot height to turbulator element height, for example a ratioof 2 to 1, may allow for improved cooling performance, while avoidingthe manufacturing challenges associated with smaller slots. For example,where a turbulator element is provided as a single radial trip-strip,improvement in cooling may be achieved. Additionally, theabove-described system may reduce the tendency of core die wear due tothe increased slot height, thereby maintaining turbine blademanufacturing tolerances and increasing turbine blade core die life. Dueto a decreased metal temperature of the turbine blade, the blade lifemay be extended, in some instances by three times. Improved cooling andextended blade life may thus be achieved with minimal core changes tothe internal flow passages of the turbine blade by incorporation of aturbulator element downstream of the slots between first and second flowpassages.

As noted above, in some embodiments the turbulator or turbulator elementmay be provided as at least one convex protrusion, or a plurality ofconvex protrusions, disposed on the peripheral wall in the secondchamber. In some embodiments, the protrusions may be formed integrallywith the peripheral wall. In yet other embodiments, as also noted above,the turbulator element may be provided as at least one concave cavity,or dimple, or a plurality of concave dimples, formed in the peripheralwall of the second chamber. A plurality of protrusions and/or dimplesmay be provided as the turbulator or turbulator element where, forexample, a radially disposed trip strip may cause excessive pressureloss in the second chamber. Protrusions and/or dimples may provide adesired turbulent flow without causing too great of a reduction inpressure.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the disclosed turbinecooling system. Other embodiments will be apparent to those skilled inthe art from consideration of the specification and practice of thedisclosed system and method. It is intended that the specification andexamples be considered as exemplary only, with a true scope beingindicated by the following claims and their equivalents.

What is claimed is:
 1. A turbine blade of a gas turbine engine, theblade comprising: a first cooling passage; a second cooling passage, thesecond cooling passage being located adjacent a leading edge of theblade; at least one slot formed in a partition disposed between thefirst and second cooling passages; and at least one turbulator disposedwithin the second passage and downstream of the at least one slot. 2.The turbine blade of claim 1, wherein the at least one turbulatorcomprises a single strip radially disposed within the second coolingpassage.
 3. The turbine blade of claim 1, wherein the at least oneturbulator includes a plurality of turbulator elements disposed withinthe second cooling passage.
 4. The turbine blade of claim 1, wherein theat least one turbulator is disposed directly downstream of the at leastone slot.
 5. The turbine blade of claim 1, wherein the at least one slotcomprises a plurality of slots, and wherein the at least one turbulatoris disposed downstream of each of the plurality of slots.
 6. The turbineblade of claim 1, wherein the at least one turbulator is connected to aperipheral wall of the turbine blade within the second cooling passage.7. The turbine blade of claim 1, wherein a height of the at least oneslot is greater than a height of the at least one turbulator.
 8. Theturbine blade of claim 1, wherein a height of the at least one slot isabout two times greater than a height of the at least one turbulator. 9.The turbine blade of claim 1, wherein a distance from an inlet openingof the at least one slot to the at least one turbulator is less thanabout four times a height of the at least one slot.
 10. The turbineblade of claim 1, wherein the at least one turbulator comprises aconcave dimple formed in a peripheral wall of the turbine blade.
 11. Asystem for cooling a turbine blade of a gas turbine engine, the systemcomprising: a first cooling path disposed in an interior of the turbineblade and configured to receive a flow of cooling fluid; a secondcooling path disposed in the interior of the turbine blade andconfigured to receive the flow of cooling fluid; a plurality of passagesforming each of the first and second cooling paths; a plurality of slotsformed in a partition disposed between two of the plurality of passagesforming the first cooling path, wherein the plurality of slots areconfigured to guide the flow of cooling fluid through the first coolingpath; and at least one turbulator disposed downstream of the flow ofcooling fluid flowing through the plurality of slots.
 12. The system ofclaim 11, wherein the at least one turbulator comprises a single stripradially disposed within one of the plurality of passages forming thefirst cooling path.
 13. The system of claim 12, wherein the at least oneturbulator is disposed directly downstream of the flow of cooling fluidflowing through the plurality of slots.
 14. The system of claim 13,wherein the at least one turbulator is disposed downstream of each ofthe plurality of slots.
 15. The system of claim 11, wherein the at leastone turbulator is connected to a peripheral wall of the turbine bladewithin one of the plurality of passages forming the first cooling pathand located adjacent a leading edge of the turbine blade.
 16. The systemof claim 11, wherein a height of each of the plurality of slots isgreater than a height of the at least one turbulator.
 17. The system ofclaim 11, wherein a distance from an inlet opening of each of theplurality of slots to the at least one turbulator is less than aboutfour times a height of each of the plurality of slots.
 18. A method ofcooling a turbine blade of a gas turbine engine, the method comprising:flowing a cooling fluid through a plurality of passages and through atleast one slot formed in a partition disposed between two of theplurality of passages; and adding turbulence to at least part of theflow of cooling fluid downstream of the at least one slot, theturbulence being adjacent a leading edge of the turbine blade.
 19. Themethod of claim 18, wherein turbulence is added to the flow of coolingfluid directly downstream of the at least one slot.
 20. The method ofclaim 18, further comprising adding turbulence to the entire flow ofcooling fluid flowing through the at least one slot.